A semi-synthetic opiate made by adding two acetyl groups to the MORPHINE molecule (see OPIATES). It was first made and promoted by Bayer Laboratories (the same company that makes Bayer aspirin) in 1898. It originally was marketed as a non-addictive substitute for CODEINE. However, as use spread, it soon became apparent that heroin was the most addictive of all the opiates (see ADDICTION). The minor chemical modification makes heroin much more potent than morphine, because it is more lipid-soluble and reaches the brain more quickly and in higher concentrations. Among the opiate addict population, heroin is the drug of choice. It is usually injected into the veins (see INTRAVENOUS SELF-ADMINISTRATION), although it is also injected beneath the skin, which is known as ‘skin-popping’. When injected intravenously, heroin is absorbed very rapidly and reaches the brain in a matter of seconds. Subjective accounts by addicts of the heroin high or ‘rush’ describe a warm flushing of the skin and sensations described in intensity and quality as a ‘whole-body ORGASM’. This initial effect lasts for less than 1 minute. TOLERANCE often develops to the EUPHORIA produced by the drug. Heroin can also induce general feelings of well-being, calmness, and a sleepy dream-like state known as ‘twilight sleep’. Feelings of ANXIETY, hostility, and AGGRESSION are reduced by heroin. Indeed, in addition to the pleasurable feelings heroin induces, its ability to blunt psychological pain may be an important motivation for using heroin.
Heroin addiction may be associated with a high degree of tolerance and PHYSICAL DEPENDENCE. With repeated use, the dose taken by the user gradually becomes higher. After continued use of fairly high doses, some users can administer doses up to 50 times what would kill a non-tolerant individual.
Physical dependence is also classically associated with heroin addiction, and a WITHDRAWAL SYNDROME results in dependent individuals upon cessation of the drug. This syndrome, which varies in intensity depending on the individual and severity of dependence, consists of a number of physiological and psychological symptoms, such as irritability, loss of APPETITE, and TREMOR. At peak intensity, the individual experiences INSOMNIA, violent yawning, excessive tearing and sneezing. Muscle weakness and depression may be pronounced. PILOERECTION resulting in ‘goosebumps’ gives the skin the appearance of a plucked turkey; hence the expression ‘cold turkey’ given to signify abrupt withdrawal. Gastrointestinal distress, characterized by cramps and diarrhoea, is also apparent. Gradually, the symptoms subside, although the neuroadaptation that takes place with long-term heroin use may subsist for months or years, and contribute to relapse. The primary treatment for heroin addiction has been pharmacological, with a fair amount of success. Maintenance or substitution therapy has involved substituting an oral synthetic opiate, usually METHADONE, for the intravenous heroin. There are a number of reasons why methadone is preferable to heroin. First, it can be taken orally and thus intravenous injection is avoided. Second, methadone is longer acting than heroin and prevents the onset of withdrawal symptoms for up to 24 hours. Third, little or no euphoria is produced by methadone. Although there is an abstinence syndrome that results from withdrawal from methadone, it is less severe in intensity than withdrawal from heroin. Moreover, methadone seems to block the effects of heroin. Several studies both in the laboratory and in street settings have shown that the heroin addict does not experience the same rush or euphoria if he does take heroin while on methadone, probably because methadone is already occupying the opiate receptors. Since the REINFORCEMENT effects of heroin are diminished and the unpleasant withdrawal state is avoided, metha-done therapy is successful in getting users off heroin.
ANN E.KELLEY
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